Using Internet service, it is possible for modern avionics that have a transmission control protocol/Internet protocol (TCP/IP) interface to download software or database directly to line replaceable units (LRU) from a remote server. However, traditional avionics and some traditional computing devices do not include the TCP/IP interface for such downloading so remote downloading becomes difficult and expensive. In legacy aircraft, data loading to avionics requires expensive manual operations, in which a technician goes to the aircraft and loads software or databases using either a personal computer memory card international association (PCMCIA) memory card or data CD through portable/installed disk drives. In order to avoid obsolescence, this operation is typically repeated at periodic intervals per the certification process defined for databases.
If the traditional avionics is migrated for TCP/IP interface, the equipment getting a new TCP/IP interface requires both hardware and software changes. Hardware may have to be upgraded with Ethernet ports and software needs to be upgraded to support TCP/IP protocol suite and software download modules. Such modifications require recertification of equipment, which is expensive.
In some avionic systems, data to be downloaded is routed through a communication management unit using existing Aeronautical Radio, Incorporated (ARINC) 429 connectivity between line replaceable units and the communication management unit, which have both been modified for software changes to accommodate the downloading. In some cases, there may not be direct ARINC 429 bus connectivity running from the communication management unit to the line replaceable units. Hence, this configuration can also require recertification of equipment.